1. Field of the Invention
The present invention relates to an apparatus and method for casting metallic strip directly from tee melt. More particularly, the invention relates to an apparatus and method for casting rapidly solidified metal strip which has improved surface quality.
2. Brief Description of the Prior Art
U.S. Pat. No. 4,221,457 to Narasimhan discloses a method and apparatus for casting amorphous metal strip which includes a slotted nozzle that has lips spaced from a moving chill surface to support a melt puddle. U.S. Pat. 4,274,473 to Bedell, et al. discloses a casting nozzle which has a first lip and a second lip. The first lip is located closer to a chill surface than the second lip. U.S. Pat. No. 4,290,476 to Smith, et al. discloses a casting nozzle which has a first lip, a second lip and two side edges. The first lip and the two side edges are closer to a chill surface than the second lip. U.S. Pat. No. 3,863,700 to Bedell, et al. discloses a method and apparatus for producing metal filament by a melt extraction technique. A discrete amount of molten metal is elevated from a melt by a gas jet directed against the surface of the melt. The elevated molten metal is forced up into contact with a quench wheel by the gas jet.
Conventional casting devices and techniques, however, have had several shortcomings. The device taught by Bedell, et al. ('700), for example, has not been able to reliably produce continuous strip having uniform thickness and width. Devices and techniques, such as those taught by Narasimhan, Smith, et al. and Bedell, et al. ('473) have been susceptible to clogging of the nozzle orifice, and are particularly sensitive to the surface finish of the downstream supporting lip. As a result, conventional devices have produced non-uniform strip and have produced strip with undesirable markings and striations on the strip surface.